Biomedical Engineering Reference
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O
O
OCH
3
H
S
Si
p
K
a (quinuclidine)
= 9.8
N
H
N
O
X
-
H
O
O
HO
CH
3
N
~1.25 μmol/m
2
(a)
O
O
S
Cl
N
HO
Si
O
O
OCH
3
O
H
S
O
2
Cl
p
K
a(SO3H)
~1.3
~0.9 μmol/m
2
(b)
HO
-60
-40
-20
0
20
40
3
4
5
6
7
8
9
10
(c)
pH
FIGURE 14.2
-potential (c)
as measured by microelectrophoresis, of native and modii ed spherical silica particles.
Experimental conditions: 10 mM KCl in 1 mM buffer; supporting particles, Kromasil 100 Å,
3.5 μm (320 m
2
/g). Rhombi, silica; circles, 3-mercaptopropyl-modii ed silica; squares, chiral
anion-exchanger (a); triangles, chiral cation-exchanger (b). Dotted line indicates recommended
pH range for chiral anion-exchanger CSP to obtain robust conditions. (Modii ed from Munoz,
O.L.S. et al.,
Electrophoresis
, 24, 390, 2003. With permission.)
Chiral anion-exchanger (a), chiral cation-exchanger (b), and their
ζ
14.4 MIGRATION AND SEPARATION MECHANISM
In the absence of electrokinetic phenomena of the second kind [14,15,25] (which is
typically realized at common ionic strengths of 10 mmol/L or higher) the observed
linear migration velocity
ν
CEC
(usually given in mm/s) in CEC can be simply approx-
imated by Equation 14.3 [5,25].
1
(
)
(14.3)
ν =ν+ν+ν ⋅
+
(
)
CEC
eo
ep
press
1
k
CLC
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